1. Field of the Invention
The present invention relates to computer peripheral equipments and more particularly, to a peripheral connector combined with boundary-scan test function.
2. Description of the Related Art
The on-board test technique to the input/output devices of an integrated circuit or printed circuit board is specified by boundary scan test of the design for test, i.e., the so-called JTAG (Joint Test Action Group) test protocol. It is the application of a scan path at each boundary (I/O) pin of on-board ICs or PCB circuits then accessing the test result for observing the circuit performance via scan operation. Therefore, the JTAG test technique consists of monitoring the I/O signalling, the integrity of interconnections, and logic operation functionality, etc. This provides a high reliability test to a circuit system.
JTAG test architecture comprises a test access port (TAP), allowing input and output of logic test command, test data, and test results, etc. Therefore, the TAP works as a serial interface accessed by an external test mainframe of a remote controller. Structurally, JTAG test architecture facilitates initial circuit design test and posterior system monitoring or serial communication application. However, because the test access port is a hardware connection port exposed to the outside of the circuit system, it is an unnecessary extra connector in a final product, for example, computer system to an ordinary user. Therefore, the manufacturer may remove the test access port to eliminate the risk of circuit contamination by the environment, or keep and hide the test access port for further use of product maintain test. However, keeping the test access port is not a good way because an additional mounting procedure is necessary when the posterior test work is required. Moreover, it degrades the efficiency of circuit design space on the circuit board as an extra circuit board space must be provided for hiding the test access port. Therefore, this method does not maintain the quality and the efficiency of practical use while keeping JTAG test function.